KEYTRUDA® (pembrolizumab) in Combination
with Inlyta® (axitinib) Reduced Risk of Death
by Nearly Half Compared to Sunitinib as First-Line Treatment for
Advanced Renal Cell Carcinoma (RCC)

Results from Phase 3 KEYNOTE-426 Study Presented Today at the 2019
Genitourinary Cancers Symposium (ASCO GU) and Published in the New
England Journal of Medicine Also Showed Risk of Progression or Death
Reduced by 31 Percent

Data Consistent Across all IMDC Risk Groups and Regardless of PD-L1
Expression

KENILWORTH, N.J.–(BUSINESS WIRE)– Merck (NYSE: MRK), known as MSD outside the United States and Canada,
today announced presentation of the full results from the pivotal Phase
3 KEYNOTE-426 trial investigating KEYTRUDA, Merck’s anti-PD-1 therapy,
in combination with Inlyta (axitinib), a tyrosine kinase inhibitor, for
the first-line treatment of advanced renal cell carcinoma (RCC) at the
2019 Genitourinary Cancers Symposium (ASCO GU) (Abstract #543). These
data were also simultaneously published in the New England Journal of
Medicine. This is the first combination regimen to significantly
improve overall survival (OS), progression-free survival (PFS) and
objective response rate (ORR) compared to sunitinib. Results were
consistent across all IMDC subgroups, including favorable, intermediate
and poor risk groups, and regardless of PD-L1 expression.

As previously announced, the U.S. Food and Drug Administration (FDA) has
granted priority review for a supplemental Biologics License Application
(sBLA) for KEYTRUDA in combination with axitinib for the first-line
treatment of patients with advanced RCC based on the results of
KEYNOTE-426, and has set a Prescription Drug User Fee Act (PDUFA), or
target action, date of June 20, 2019.

“Historically, patients with advanced RCC have faced five-year survival
rates of less than 10 percent. Given the aggressive nature of this
disease and the poor long-term prognosis, these new survival data with
KEYTRUDA in combination with axitinib from KEYNOTE-426 offer the
potential of a new treatment option for patients with advanced renal
cell carcinoma,” said Dr. Thomas Powles, lead investigator for
KEYNOTE-426, professor of genitourinary oncology, lead for Solid Tumor
Research at Barts Cancer Institute, director of Barts Cancer Centre.

Findings from the first interim analysis showed KEYTRUDA in combination
with axitinib reduced the risk of death by 47 percent – significantly
improving OS compared to sunitinib (HR=0.53 [95% CI, 0.38-0.74];
p<0.0001). For the dual primary endpoint of PFS, the KEYTRUDA
combination showed a reduction in the risk of progression of disease or
death of 31 percent compared to sunitinib (HR=0.69 [95% CI, 0.57-0.84];
p=0.0001). In the study, the ORR was 59.3 percent for patients who
received KEYTRUDA in combination with axitinib (95% CI, 54.5-63.9) and
35.7 percent for those who received sunitinib (95% CI, 31.1-40.4)
(p<0.0001), with a complete response rate of 5.8 percent (n=25) and 1.9
percent (n=8) and a partial response rate of 53.5 percent (n=231) and
33.8 percent (n=145), for patients receiving the KEYTRUDA combination or
sunitinib, respectively. Median duration of response was not reached in
the KEYTRUDA combination arm (range, 1.4+ to 18.2+ months) and was 15.2
months (range, 1.1+ to 15.4+) in the sunitinib arm. The results for OS,
PFS and ORR were consistent across all IMDC risk groups and seen
regardless of PD-L1 expression. The observed adverse event profile was
as expected based on the known profiles of KEYTRUDA and axitinib. There
was a higher incidence of grade 3 or 4 liver enzyme elevation with
KEYTRUDA plus axitinib than previously observed with each agent as
monotherapy.

“With a reduction in the risk of death by nearly half, these findings
are particularly impressive considering the benefit was not limited to
one subgroup of patients – we observed an overall survival improvement
across all IMDC risk groups and regardless of PD-L1 expression,” said
Dr. Roy Baynes, senior vice president and head of global clinical
development, chief medical officer, Merck Research Laboratories. “We are
pleased that these findings have been accepted for priority review by
the FDA, and hopeful that they will be viewed positively by regulatory
authorities worldwide. In the meantime, we are grateful to the
investigators and patients for their involvement in this important
study.”

« These data build on the single-agent activity of pembrolizumab and
axitinib, and represent the first time a kidney cancer regimen has
improved overall survival, progression-free survival and objective
response rate versus sunitinib. More importantly, they offer patients
with this aggressive form of kidney cancer a potential new first-line
treatment option,” said Dr. Brian Rini, lead author for the New
England Journal of Medicine publication of KEYNOTE-426, medical
oncologist at Cleveland Clinic Cancer Center and professor of medicine
at the Cleveland Clinic Lerner College of Medicine of Case Western
Reserve University. As reported by the Cleveland Clinic, Dr. Rini
reports consulting and research funding from Merck.

Merck has filed these data with regulatory authorities worldwide. Merck
has an extensive clinical development program in RCC and is advancing
multiple potential registration-enabling studies with KEYTRUDA, as
monotherapy and in combination with other treatments, including
KEYNOTE-564 and KEYNOTE-581.

Study Design and Additional Data from KEYNOTE-426

KEYNOTE-426 is a randomized, double-arm, Phase 3 trial
(ClinicalTrials.gov, NCT02853331) evaluating the safety and efficacy of
KEYTRUDA in combination with axitinib as first-line treatment for
advanced or metastatic RCC compared to sunitinib monotherapy. The dual
primary endpoints of the study were OS and PFS; key secondary endpoints
include ORR, safety, duration of response, PFS at 12, 18 and 24 months
and OS at 12, 18 and 24 months. The primary outcome measures were
further evaluated based on PD-L1 tumor expression (combined positive
score [CPS] <1 [n=325] and ?1 [n=497]). In the trial, 861 patients
determined to be favorable-, intermediate- or poor-risk by IMDC criteria
(n=269, n=484, n=108, respectively) were randomly assigned to receive
KEYTRUDA 200 mg intravenously every three weeks plus axitinib 5 mg
orally twice daily for up to 24 months (n=432), or sunitinib 50 mg
orally once daily for four weeks followed by no treatment for two weeks
(n=429).

At the first interim analysis, after a median follow-up of 12.8 months,
overall survival was significantly longer in the KEYTRUDA combination
arm than in the sunitinib arm (HR=0.53 [95% CI, 0.38-0.74]; p<0.0001).
Estimated 12-month survival rates were 89.9 percent (95% CI, 86.4-92.4)
in the KEYTRUDA combination arm compared to 78.3 percent (95% CI,
73.8-82.1) in the sunitinib arm; the 18-month survival estimates were
82.3 percent (95% CI, 77.2-86.3) and 72.1 percent (95% CI, 66.3-77.0),
respectively. Median survival was not reached in either group.
Progression-free survival was also significantly longer in the KEYTRUDA
combination arm than in the sunitinib arm (HR=0.69 [95% CI, 0.57-0.84];
p=0.0001). The 12-month PFS rate was 59.6 percent in the KEYTRUDA
combination arm and 46.2 percent in the sunitinib arm; the 18-month PFS
rate was 41.1 percent in the KEYTRUDA combination arm and 32.9 percent
in the sunitinib arm. Median PFS was 15.1 months (95% CI, 12.6-17.7) in
the KEYTRUDA combination arm compared to 11.1 months (95% CI, 8.7-12.5)
in the sunitinib arm.

Grade 3-5 treatment-related adverse events (TRAEs) occurred in 62.9
percent of the 429 treated patients in the KEYTRUDA combination arm and
58.1 percent of the 425 treated patients in the sunitinib arm. TRAEs
resulting in discontinuation of any treatment occurred in 25.9 percent
of patients in the KEYTRUDA combination arm and 10.1 percent of patients
in the sunitinib arm; 8.2 percent of patients discontinued both KEYTRUDA
and axitinib. The most common grade 3-5 TRAEs (occurring in ?10% of
patients) were hypertension (22.1%) and increased alanine
aminotransferase (ALT) (13.3%) in the KEYTRUDA combination arm and
hypertension (19.3%) in the sunitinib arm.

Renal cell carcinoma is by far the most common type of kidney cancer;
about 9 out of 10 kidney cancers are RCCs. Renal cell carcinoma is about
twice as common in men as in women. Modifiable risk factors include
smoking, obesity, workplace exposure to certain substances and high
blood pressure. There were approximately 403,000 cases of kidney cancer
diagnosed worldwide in 2018 and about 175,000 deaths from the disease.
In the U.S. alone, there will be an estimated 74,000 new cases of kidney
cancer diagnosed in 2019 and about 15,000 people will die from the
disease.

About KEYTRUDA® (pembrolizumab) Injection,
100mg

KEYTRUDA is an anti-PD-1 therapy that works by increasing the ability of
the body’s immune system to help detect and fight tumor cells. KEYTRUDA
is a humanized monoclonal antibody that blocks the interaction between
PD-1 and its ligands, PD-L1 and PD-L2, thereby activating T lymphocytes
which may affect both tumor cells and healthy cells.

Merck has the industry’s largest immuno-oncology clinical research
program. There are currently more than 900 trials studying KEYTRUDA
across a wide variety of cancers and treatment settings. The KEYTRUDA
clinical program seeks to understand the role of KEYTRUDA across cancers
and the factors that may predict a patient’s likelihood of benefitting
from treatment with KEYTRUDA, including exploring several different
biomarkers.

KEYTRUDA® (pembrolizumab) Indications and
Dosing

Melanoma

KEYTRUDA is indicated for the treatment of patients with unresectable or
metastatic melanoma at a fixed dose of 200 mg every three weeks until
disease progression or unacceptable toxicity.

Lung Cancer

KEYTRUDA, in combination with pemetrexed and platinum chemotherapy, is
indicated for the first-line treatment of patients with metastatic
nonsquamous non-small cell lung cancer (NSCLC), with no EGFR or ALK
genomic tumor aberrations.

KEYTRUDA, in combination with carboplatin and either paclitaxel or
nab-paclitaxel, is indicated for the first-line treatment of patients
with metastatic squamous NSCLC.

KEYTRUDA, as a single agent, is indicated for the first-line treatment
of patients with metastatic NSCLC whose tumors have high PD-L1
expression [Tumor Proportion Score (TPS) ?50%] as determined by an
FDA-approved test, with no EGFR or ALKgenomic tumor aberrations.

KEYTRUDA, as a single agent, is indicated for the treatment of patients
with metastatic NSCLC whose tumors express PD-L1 (TPS ?1%) as determined
by an FDA-approved test, with disease progression on or after
platinum-containing chemotherapy. Patients with EGFR or ALK genomic
tumor aberrations should have disease progression on FDA-approved
therapy for these aberrations prior to receiving KEYTRUDA.

In metastatic NSCLC, the recommended dose of KEYTRUDA is 200 mg
administered as an intravenous infusion over 30 minutes every three
weeks until disease progression, unacceptable toxicity, or up to 24
months in patients without disease progression.

When administering KEYTRUDA in combination with chemotherapy, KEYTRUDA
should be administered prior to chemotherapy when given on the same day.
See also the Prescribing Information for the chemotherapy agents
administered in combination with KEYTRUDA, as appropriate.

Head and Neck Cancer

KEYTRUDA is indicated for the treatment of patients with recurrent or
metastatic head and neck squamous cell carcinoma (HNSCC) with disease
progression on or after platinum-containing chemotherapy. This
indication is approved under accelerated approval based on tumor
response rate and durability of response. Continued approval for this
indication may be contingent upon verification and description of
clinical benefit in the confirmatory trials. In HNSCC, KEYTRUDA is
administered as an intravenous infusion over 30 minutes of 200 mg every
three weeks until disease progression, unacceptable toxicity, or up to
24 months in patients without disease progression.

Classical Hodgkin Lymphoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients
with refractory classical Hodgkin lymphoma (cHL), or who have relapsed
after 3 or more prior lines of therapy. This indication is approved
under accelerated approval based on tumor response rate and durability
of response. Continued approval for this indication may be contingent
upon verification and description of clinical benefit in the
confirmatory trials. In adults with cHL, KEYTRUDA is administered as an
intravenous infusion over 30 minutes of 200 mg every three weeks until
disease progression or unacceptable toxicity, or up to 24 months in
patients without disease progression. In pediatric patients with cHL,
KEYTRUDA is administered as an intravenous infusion over 30 minutes at a
dose of 2 mg/kg (up to a maximum of 200 mg) every three weeks until
disease progression or unacceptable toxicity, or up to 24 months in
patients without disease progression.

Primary Mediastinal Large B-Cell Lymphoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients
with refractory primary mediastinal large B-cell lymphoma (PMBCL), or
who have relapsed after 2 or more prior lines of therapy. This
indication is approved under accelerated approval based on tumor
response rate and durability of response. Continued approval for this
indication may be contingent upon verification and description of
clinical benefit in confirmatory trials. KEYTRUDA is not recommended for
the treatment of patients with PMBCL who require urgent cytoreductive
therapy.

In adults with PMBCL, KEYTRUDA is administered as an intravenous
infusion over 30 minutes of 200 mg every three weeks until disease
progression, unacceptable toxicity, or up to 24 months in patients
without disease progression. In pediatric patients with PMBCL, KEYTRUDA
is administered as an intravenous infusion over 30 minutes at a dose of
2 mg/kg (up to a maximum of 200 mg) every three weeks until disease
progression or unacceptable toxicity, or up to 24 months in patients
without disease progression.

Urothelial Carcinoma

KEYTRUDA is indicated for the treatment of patients with locally
advanced or metastatic urothelial carcinoma (mUC) who are not eligible
for cisplatin-containing chemotherapy and whose tumors express PD-L1
[Combined Positive Score (CPS) ?10] as determined by an FDA-approved
test, or in patients who are not eligible for any platinum-containing
chemotherapy regardless of PD-L1 status. This indication is approved
under accelerated approval based on tumor response rate and duration of
response. Continued approval for this indication may be contingent upon
verification and description of clinical benefit in the confirmatory
trials.

KEYTRUDA is indicated for the treatment of patients with locally
advanced or metastatic urothelial carcinoma (mUC) who have disease
progression during or following platinum-containing chemotherapy or
within 12 months of neoadjuvant or adjuvant treatment with
platinum-containing chemotherapy.

In locally advanced or metastatic urothelial carcinoma, KEYTRUDA is
administered as an intravenous infusion over 30 minutes of 200 mg every
three weeks until disease progression or unacceptable toxicity, or up to
24 months in patients without disease progression.

Microsatellite Instability-High (MSI-H) Cancer

KEYTRUDA is indicated for the treatment of adult and pediatric patients
with unresectable or metastatic microsatellite instability-high (MSI-H)
or mismatch repair deficient (dMMR)

solid tumors that have progressed following prior treatment and who
have no satisfactory alternative treatment options, or

colorectal cancer that has progressed following treatment with
fluoropyrimidine, oxaliplatin, and irinotecan.

This indication is approved under accelerated approval based on tumor
response rate and durability of response. Continued approval for this
indication may be contingent upon verification and description of
clinical benefit in the confirmatory trials. The safety and
effectiveness of KEYTRUDA in pediatric patients with MSI-H central
nervous system cancers have not been established.

In adult patients with MSI-H cancer, KEYTRUDA is administered as an
intravenous infusion over 30 minutes of 200 mg every three weeks until
disease progression, unacceptable toxicity, or up to 24 months in
patients without disease progression. In children with MSI-H cancer,
KEYTRUDA is administered as an intravenous infusion over 30 minutes at a
dose of 2 mg/kg (up to a maximum of 200 mg) every three weeks until
disease progression or unacceptable toxicity, or up to 24 months in
patients without disease progression.

Gastric Cancer

KEYTRUDA is indicated for the treatment of patients with recurrent
locally advanced or metastatic gastric or gastroesophageal junction
(GEJ) adenocarcinoma whose tumors express PD-L1 [Combined Positive Score
(CPS) ?1] as determined by an FDA-approved test, with disease
progression on or after two or more prior lines of therapy including
fluoropyrimidine- and platinum-containing chemotherapy and if
appropriate, HER2/neu-targeted therapy. This indication is approved
under accelerated approval based on tumor response rate and durability
of response. Continued approval for this indication may be contingent
upon verification and description of clinical benefit in the
confirmatory trials. The recommended dose of KEYTRUDA is an intravenous
infusion over 30 minutes of 200 mg every three weeks until disease
progression, unacceptable toxicity, or up to 24 months in patients
without disease progression.

Cervical Cancer

KEYTRUDA is indicated for the treatment of patients with recurrent or
metastatic cervical cancer with disease progression on or after
chemotherapy whose tumors express PD-L1 (CPS ?1) as determined by an
FDA-approved test. This indication is approved under accelerated
approval based on tumor response rate and durability of response.
Continued approval for this indication may be contingent upon
verification and description of clinical benefit in the confirmatory
trials. The recommended dose of KEYTRUDA is an intravenous infusion over
30 minutes of 200 mg every three weeks until disease progression,
unacceptable toxicity, or up to 24 months in patients without disease
progression.

Hepatocellular Carcinoma

KEYTRUDA is indicated for the treatment of patients with hepatocellular
carcinoma (HCC) who have been previously treated with sorafenib. This
indication is approved under accelerated approval based on tumor
response rate and durability of response. Continued approval for this
indication may be contingent upon verification and description of
clinical benefit in the confirmatory trials. The recommended dose of
KEYTRUDA is an intravenous infusion over 30 minutes of 200 mg every
three weeks until disease progression, unacceptable toxicity, or up to
24 months in patients without disease progression.

Merkel Cell Carcinoma

KEYTRUDA is indicated for the treatment of adult and pediatric patients
with recurrent locally advanced or metastatic Merkel cell carcinoma.
This indication is approved under accelerated approval based on tumor
response rate and durability of response. Continued approval for this
indication may be contingent upon verification and description of
clinical benefit in the confirmatory trials. The recommended dose of
KEYTRUDA in adults is 200 mg administered as an intravenous infusion
over 30 minutes every three weeks until disease progression,
unacceptable toxicity, or up to 24 months in patients without disease
progression. The recommended dose of KEYTRUDA in pediatric patients is 2
mg/kg (up to a maximum of 200 mg), administered as an intravenous
infusion over 30 minutes every three weeks until disease progression or
unacceptable toxicity, or up to 24 months in patients without disease
progression.

KEYTRUDA can cause hypophysitis, thyroid disorders, and type 1 diabetes
mellitus. Hypophysitis occurred in 0.6% (17/2799) of patients, including
Grade 2 (0.2%), 3 (0.3%), and 4 (<0.1%). Hypothyroidism occurred in 8.5%
(237/2799) of patients, including Grade 2 (6.2%) and 3 (0.1%). The
incidence of new or worsening hypothyroidism was higher in patients with
HNSCC, occurring in 15% (28/192) of patients. Hyperthyroidism occurred
in 3.4% (96/2799) of patients, including Grade 2 (0.8%) and 3 (0.1%),
and thyroiditis occurred in 0.6% (16/2799) of patients, including Grade
2 (0.3%). Type 1 diabetes mellitus, including diabetic ketoacidosis,
occurred in 0.2% (6/2799) of patients.

Monitor patients for signs and symptoms of hypophysitis (including
hypopituitarism and adrenal insufficiency), thyroid function (prior to
and periodically during treatment), and hyperglycemia. For hypophysitis,
administer corticosteroids and hormone replacement as clinically
indicated. Withhold KEYTRUDA for Grade 2 and withhold or discontinue for
Grade 3 or 4 hypophysitis. Administer hormone replacement for
hypothyroidism and manage hyperthyroidism with thionamides and
beta-blockers as appropriate. Withhold or discontinue KEYTRUDA for Grade
3 or 4 hyperthyroidism. Administer insulin for type 1 diabetes, and
withhold KEYTRUDA and administer antihyperglycemics in patients with
severe hyperglycemia.

Immune-mediated rashes, including Stevens-Johnson syndrome (SJS), toxic
epidermal necrolysis (TEN) (some cases with fatal outcome), exfoliative
dermatitis, and bullous pemphigoid, can occur. Monitor patients for
suspected severe skin reactions and based on the severity of the adverse
reaction, withhold or permanently discontinue KEYTRUDA and administer
corticosteroids. For signs or symptoms of SJS or TEN, withhold KEYTRUDA
and refer the patient for specialized care for assessment and treatment.
If SJS or TEN is confirmed, permanently discontinue KEYTRUDA.

Other Immune-Mediated Adverse Reactions

Immune-mediated adverse reactions, which may be severe or fatal, can
occur in any organ system or tissue in patients receiving KEYTRUDA and
may also occur after discontinuation of treatment. For suspected
immune-mediated adverse reactions, ensure adequate evaluation to confirm
etiology or exclude other causes. Based on the severity of the adverse
reaction, withhold KEYTRUDA and administer corticosteroids. Upon
improvement to Grade 1 or less, initiate corticosteroid taper and
continue to taper over at least 1 month. Based on limited data from
clinical studies in patients whose immune-related adverse reactions
could not be controlled with corticosteroid use, administration of other
systemic immunosuppressants can be considered. Resume KEYTRUDA when the
adverse reaction remains at Grade 1 or less following corticosteroid
taper. Permanently discontinue KEYTRUDA for any Grade 3 immune-mediated
adverse reaction that recurs and for any life-threatening
immune-mediated adverse reaction.

Treatment with KEYTRUDA may increase the risk of rejection in solid
organ transplant recipients. Consider the benefit of treatment vs the
risk of possible organ rejection in these patients.

Infusion-Related Reactions

KEYTRUDA can cause severe or life-threatening infusion-related
reactions, including hypersensitivity and anaphylaxis, which have been
reported in 0.2% (6/2799) of patients. Monitor patients for signs and
symptoms of infusion-related reactions. For Grade 3 or 4 reactions, stop
infusion and permanently discontinue KEYTRUDA.

Immune-mediated complications, including fatal events, occurred in
patients who underwent allogeneic HSCT after treatment with KEYTRUDA. Of
23 patients with cHL who proceeded to allogeneic HSCT after KEYTRUDA, 6
developed graft-versus-host disease (GVHD) (1 fatal case) and 2
developed severe hepatic veno-occlusive disease (VOD) after
reduced-intensity conditioning (1 fatal case). Cases of fatal hyperacute
GVHD after allogeneic HSCT have also been reported in patients with
lymphoma who received a PD-1 receptor–blocking antibody before
transplantation. Follow patients closely for early evidence of
transplant-related complications such as hyperacute graft-versus-host
disease (GVHD), Grade 3 to 4 acute GVHD, steroid-requiring febrile
syndrome, hepatic veno-occlusive disease (VOD), and other
immune-mediated adverse reactions.

In patients with a history of allogeneic HSCT, acute GVHD (including
fatal GVHD) has been reported after treatment with KEYTRUDA. Patients
who experienced GVHD after their transplant procedure may be at
increased risk for GVHD after KEYTRUDA. Consider the benefit of KEYTRUDA
vs the risk of GVHD in these patients.

Increased Mortality in Patients With Multiple Myeloma

In trials in patients with multiple myeloma, the addition of KEYTRUDA to
a thalidomide analogue plus dexamethasone resulted in increased
mortality. Treatment of these patients with a PD-1 or PD-L1 blocking
antibody in this combination is not recommended outside of controlled
trials.

Embryofetal Toxicity

Based on its mechanism of action, KEYTRUDA can cause fetal harm when
administered to a pregnant woman. Advise women of this potential risk.
In females of reproductive potential, verify pregnancy status prior to
initiating KEYTRUDA and advise them to use effective contraception
during treatment and for 4 months after the last dose.

Adverse Reactions

In KEYNOTE-006, KEYTRUDA was discontinued due to adverse reactions in 9%
of 555 patients with advanced melanoma; adverse reactions leading to
permanent discontinuation in more than one patient were colitis (1.4%),
autoimmune hepatitis (0.7%), allergic reaction (0.4%), polyneuropathy
(0.4%), and cardiac failure (0.4%). The most common adverse reactions
(?20%) with KEYTRUDA were fatigue (28%), diarrhea (26%), rash (24%), and
nausea (21%).

In KEYNOTE-189, when KEYTRUDA was administered with pemetrexed and
platinum chemotherapy in metastatic nonsquamous NSCLC, KEYTRUDA was
discontinued due to adverse reactions in 20% of 405 patients. The most
common adverse reactions resulting in permanent discontinuation of
KEYTRUDA were pneumonitis (3%) and acute kidney injury (2%). The most
common adverse reactions (?20%) with KEYTRUDA were nausea (56%), fatigue
(56%), constipation (35%), diarrhea (31%), decreased appetite (28%),
rash (25%), vomiting (24%), cough (21%), dyspnea (21%), and pyrexia
(20%).

In KEYNOTE-407, when KEYTRUDA was administered with carboplatin and
either paclitaxel or nab-paclitaxel in metastatic squamous NSCLC,
KEYTRUDA was discontinued due to adverse reactions in 15% of 101
patients. The most frequent serious adverse reactions reported in at
least 2% of patients were febrile neutropenia, pneumonia, and urinary
tract infection. Adverse reactions observed in KEYNOTE-407 were similar
to those observed in KEYNOTE-189 with the exception that increased
incidences of alopecia (47% vs 36%) and peripheral neuropathy (31% vs
25%) were observed in the KEYTRUDA and chemotherapy arm compared to the
placebo and chemotherapy arm in KEYNOTE-407.

In KEYNOTE-010, KEYTRUDA monotherapy was discontinued due to adverse
reactions in 8% of 682 patients with metastatic NSCLC. The most common
adverse event resulting in permanent discontinuation of KEYTRUDA was
pneumonitis (1.8%). The most common adverse reactions (?20%) were
decreased appetite (25%), fatigue (25%), dyspnea (23%), and nausea (20%).

In KEYNOTE-012, KEYTRUDA was discontinued due to adverse reactions in
17% of 192 patients with HNSCC. Serious adverse reactions occurred in
45% of patients. The most frequent serious adverse reactions reported in
at least 2% of patients were pneumonia, dyspnea, confusional state,
vomiting, pleural effusion, and respiratory failure. The most common
adverse reactions (?20%) were fatigue, decreased appetite, and dyspnea.
Adverse reactions occurring in patients with HNSCC were generally
similar to those occurring in patients with melanoma or NSCLC who
received KEYTRUDA as a monotherapy, with the exception of increased
incidences of facial edema and new or worsening hypothyroidism.

In KEYNOTE-087, KEYTRUDA was discontinued due to adverse reactions in 5%
of 210 patients with cHL. Serious adverse reactions occurred in 16% of
patients; those ?1% included pneumonia, pneumonitis, pyrexia, dyspnea,
GVHD, and herpes zoster. Two patients died from causes other than
disease progression; 1 from GVHD after subsequent allogeneic HSCT and 1
from septic shock. The most common adverse reactions (?20%) were fatigue
(26%), pyrexia (24%), cough (24%), musculoskeletal pain (21%), diarrhea
(20%), and rash (20%).

In KEYNOTE-170, KEYTRUDA was discontinued due to adverse reactions in 8%
of 53 patients with PMBCL. Serious adverse reactions occurred in 26% of
patients and included arrhythmia (4%), cardiac tamponade (2%),
myocardial infarction (2%), pericardial effusion (2%), and pericarditis
(2%). Six (11%) patients died within 30 days of start of treatment. The
most common adverse reactions (?20%) were musculoskeletal pain (30%),
upper respiratory tract infection and pyrexia (28% each), cough (26%),
fatigue (23%), and dyspnea (21%).

In KEYNOTE-045, KEYTRUDA was discontinued due to adverse reactions in 8%
of 266 patients with locally advanced or metastatic urothelial
carcinoma. The most common adverse reaction resulting in permanent
discontinuation of KEYTRUDA was pneumonitis (1.9%). Serious adverse
reactions occurred in 39% of KEYTRUDA-treated patients; those ?2% were
urinary tract infection, pneumonia, anemia, and pneumonitis. The most
common adverse reactions (?20%) in patients who received KEYTRUDA were
fatigue (38%), musculoskeletal pain (32%), pruritus (23%), decreased
appetite (21%), nausea (21%), and rash (20%).

Adverse reactions occurring in patients with gastric cancer were similar
to those occurring in patients with melanoma or NSCLC who received
KEYTRUDA as a monotherapy.

Adverse reactions occurring in patients with HCC were generally similar
to those in patients with melanoma or NSCLC who received KEYTRUDA as a
monotherapy, with the exception of increased incidences of ascites (8%
Grades 3-4) and immune-mediated hepatitis (2.9%). Laboratory
abnormalities (Grades 3-4) that occurred at a higher incidence were
elevated AST (20%), ALT (9%), and hyperbilirubinemia (10%).

Among the 50 patients with MCC enrolled in study KEYNOTE-017, adverse
reactions occurring in patients with MCC were generally similar to those
occurring in patients with melanoma or NSCLC who received KEYTRUDA as a
monotherapy. Laboratory abnormalities (Grades 3-4) that occurred at a
higher incidence were elevated AST (11%) and hyperglycemia (19%).

Lactation

Because of the potential for serious adverse reactions in breastfed
children, advise women not to breastfeed during treatment and for 4
months after the final dose.

Pediatric Use

There is limited experience in pediatric patients. In a trial, 40
pediatric patients (16 children aged 2 years to younger than 12 years
and 24 adolescents aged 12 years to 18 years) with various cancers,
including unapproved usages, were administered KEYTRUDA 2 mg/kg every 3
weeks. Patients received KEYTRUDA for a median of 3 doses (range 1–17
doses), with 34 patients (85%) receiving 2 doses or more. The safety
profile in these pediatric patients was similar to that seen in adults;
adverse reactions that occurred at a higher rate (?15% difference) in
these patients when compared to adults under 65 years of age were
fatigue (45%), vomiting (38%), abdominal pain (28%), increased
transaminases (28%), and hyponatremia (18%).

Merck’s Focus on Cancer

Our goal is to translate breakthrough science into innovative oncology
medicines to help people with cancer worldwide. At Merck, the potential
to bring new hope to people with cancer drives our purpose and
supporting accessibility to our cancer medicines is our commitment. As
part of our focus on cancer, Merck is committed to exploring the
potential of immuno-oncology with one of the largest development
programs in the industry across more than 30 tumor types. We also
continue to strengthen our portfolio through strategic acquisitions and
are prioritizing the development of several promising oncology
candidates with the potential to improve the treatment of advanced
cancers. For more information about our oncology clinical trials, visit www.merck.com/clinicaltrials.

About Merck

For more than a century, Merck, a leading global biopharmaceutical
company known as MSD outside of the United States and Canada, has been
inventing for life, bringing forward medicines and vaccines for many of
the world’s most challenging diseases. Through our prescription
medicines, vaccines, biologic therapies and animal health products, we
work with customers and operate in more than 140 countries to deliver
innovative health solutions. We also demonstrate our commitment to
increasing access to health care through far-reaching policies, programs
and partnerships. Today, Merck continues to be at the forefront of
research to advance the prevention and treatment of diseases that
threaten people and communities around the world – including cancer,
cardio-metabolic diseases, emerging animal diseases, Alzheimer’s disease
and infectious diseases including HIV and Ebola. For more information,
visit www.merck.com and connect
with us on Twitter,Facebook,Instagram,YouTube
and LinkedIn.

Forward-Looking Statement of Merck & Co., Inc., Kenilworth, N.J., USA

This news release of Merck & Co., Inc., Kenilworth, N.J., USA (the
“company”) includes “forward-looking statements” within the meaning of
the safe harbor provisions of the U.S. Private Securities Litigation
Reform Act of 1995. These statements are based upon the current beliefs
and expectations of the company’s management and are subject to
significant risks and uncertainties. There can be no guarantees with
respect to pipeline products that the products will receive the
necessary regulatory approvals or that they will prove to be
commercially successful. If underlying assumptions prove inaccurate or
risks or uncertainties materialize, actual results may differ materially
from those set forth in the forward-looking statements.

Risks and uncertainties include but are not limited to, general industry
conditions and competition; general economic factors, including interest
rate and currency exchange rate fluctuations; the impact of
pharmaceutical industry regulation and health care legislation in the
United States and internationally; global trends toward health care cost
containment; technological advances, new products and patents attained
by competitors; challenges inherent in new product development,
including obtaining regulatory approval; the company’s ability to
accurately predict future market conditions; manufacturing difficulties
or delays; financial instability of international economies and
sovereign risk; dependence on the effectiveness of the company’s patents
and other protections for innovative products; and the exposure to
litigation, including patent litigation, and/or regulatory actions.

The company undertakes no obligation to publicly update any
forward-looking statement, whether as a result of new information,
future events or otherwise. Additional factors that could cause results
to differ materially from those described in the forward-looking
statements can be found in the company’s 2017 Annual Report on Form 10-K
and the company’s other filings with the Securities and Exchange
Commission (SEC) available at the SEC’s Internet site (www.sec.gov).